Damper assemblies are used in vehicle suspension systems to dissipate the energy of road forces applied to vehicle wheels in order to control the transmission of forces to the unsprung mass of the vehicle. Some suspension systems are passive, so that pre-load, spring rate, and ride height of the vehicle are nonadjustable, single predetermined values determined by the design of the damper assembly. In some systems, pre-load, spring rate, and ride height are variable, but not all in a controlled manner. Other suspension systems are actively controlled, so that ride height of the vehicle can be varied. Still other suspension systems allow adjustment of the spring rate or of the pre-load.